diff --git a/graphics.hh b/graphics.hh
index 1e919bc..ee55c9f 100644
--- a/graphics.hh
+++ b/graphics.hh
@@ -1,3 +1,8 @@
+#ifndef GRAPHICS_HH_INCLUDED
+#define GRAPHICS_HH_INCLUDED
+
+#endif
+
 // gets called after the OpenGL window is prepared, init of example specific stuff:
 void initCustomResources();